package com.hmdp.utils;

import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.stereotype.Component;

import javax.annotation.Resource;
import java.time.LocalDateTime;
import java.time.ZoneOffset;
import java.time.format.DateTimeFormatter;
import java.util.zip.DataFormatException;

/**
 * @author 枝枝
 * @date 2023/7/15
 * 全局ID生成器
 */
@Component
public class RedisIdWorker {

    /**
     * 开始的时间戳
     */
    private static final Long START_TIMESTAMP = 1672531200L;

    /**
     * 序列号的位数
     */
    private static final int COUNT_BITS = 32;

    @Resource
    private StringRedisTemplate stringRedisTemplate;

    public long nextId(String keyPrefix) {
        //生成时间戳
        LocalDateTime now = LocalDateTime.now();
        long epochSecond = now.toEpochSecond(ZoneOffset.UTC);
        long timestamp = epochSecond - START_TIMESTAMP;

        //生成序列号
        String data = now.format(DateTimeFormatter.ofPattern("yyyy:MM:Dd"));
        Long increment = stringRedisTemplate.opsForValue().increment("icr:" + keyPrefix + ":" + data);

        //将时间戳左移COUNT_BITS位后与自增值相结合，生成下一个标识符。
        return timestamp << COUNT_BITS | increment;
    }
}
